This proposed five year longitudinal project has two major goals. The first is to examine psychosocial (personality, family, peer, context) factors related to HIV transmission behavior in intravenous drug users to determine if there are differences between those who engage in these behaviors and those who do not. Of particular interest will be comparisons between those already infected with AIDS and those who have tested negative. It may be that different factors explain continued transmission behavior in infected individuals who continue to place themselves at risk for infection. The second major goal is to determine whether certain interpersonal (family, peer, context) factors can help individuals cope more effectively at different stages of AIDS, starting with those who test negative but must deal with being at-risk for infection and ending with those most severely ill from the disease. The sample for this study will consist of 400 male intravenous drug users recruited from outpatient Methadone and AIDS clinics in a large city hospital. They will be mainly in their 30s, ethnically-mixed, and from SES backgrounds. Face-to-face structured interviews will be conducted with the subjects twice. In addition, validation data will be collected from "significant others" in the subjects' lives. The longitudinal design of the study is essential in order to sort out emotional state may vary widely over time given the nature of HIV infection. The basic methodology to be used for data analysis is derived from extensive research in the drug field and will consist primarily of causal analysis and/or hierarchical multiple regression, and standard multiple logistic regression analysis. the significance of this project is two-fold. First, the designation of specific factors that lead to decreased transmission behavior should greatly assist in more effective targeting of public health efforts to slow or prevent HIV contagion in high risk groups. Second, given the large number of people who currently (and in the future) must deal with having, or being at risk for, AIDS, it is crucial to discover ways for health practitioners to strengthen the ability of patients to cope with the enormous life stresses attendant upon the disease. It is anticipated that this project will provide specific, practical guidelines for more efficient coping during all phases of HIV disease. The proposed grant would supplement Dr. Judith Brook's Research Scientist Development Award (K02DA00094-07).